The present invention generally relates to a rewinder system, such as the type used to rewind tissues or other paper webs from a supply web onto a core. More particularly, the present invention is directed to a rewinder system having a number of mandrels that can be indexed by a turret assembly. The mandrels can be supplied with vacuum or positive air pressure to aid in the winding process.
Various paper products, such as tissues and other paper webs, are typically formed into large supply rolls after being manufactured. In order to commercially utilize paper from these supply rolls, it is necessary to rewind the paper from the large supply roll onto a smaller sized roll, which is generally more useful for commercial purposes. For example, in conventional systems, a core is often placed onto a mandrel that is capable of spinning so that the spinning of the mandrel in conjunction with the core can effectuate winding of the paper thereon.
Techniques for utilizing mandrels for winding paper are generally well known in the art. For example, a turret-style winding system is one well-known method used to wind paper onto a core. Most turret systems include a number of mandrels that are each capable of spinning independently of each other so that multiple paper logs can be formed simultaneously. For example, in some conventional turret systems, a core is first loaded onto a mandrel. After loading, the mandrel and core can be spun so that a sheet of paper can be wound around the core. Once the desired amount of paper is wound onto the core, the core and paper can then be removed.
To effectively utilize a turret-style winding system, such as discussed above, it is generally necessary to ensure that the core remain securely fit onto the mandrel during spinning. If the core moves slightly about the mandrel while the paper is being wound, the paper might improperly wind onto the core, forming an undesirable asymmetrically wound roll.
In the past, various techniques were utilized to keep the core in a fixed position relative to the mandrel. For example, in some systems, mechanically operated dogs that cut into the core were used to maintain the position of the core relative to the mandrel. In order to support such mechanically operated dog systems, it was typically required that the mandrels be made from steel or some other heavy material. However, the use of steel and other heavy materials caused the mandrels to rotate and index about the turret at slower speeds, and thus, produced fewer paper logs per minute. Moreover, these dog systems often caused damage to the cores.
As such, a need currently exists for an improved system for winding paper onto a core. In particular, a need exists for a turret-style system for winding paper onto a core utilizing lighter mandrels to which a core can be securely placed so that the production of logs of paper per minute can increase in comparison to conventional systems.
The present invention recognizes and addresses the foregoing problems and others experienced in the prior art.
Accordingly, an object of the present invention is to provide an improved mandrel system for winding paper.
It is another object of the present invention to provide a mandrel system that can include a turret assembly having mandrels made from light materials, such as aluminum.
Still another object of the present invention is to provide a mandrel system that can include a turret assembly and a gas circulation system.
Yet another object of the present invention is to provide a gas circulation system for applying suction forces and positive pressure to a mandrel to aid in the positioning and maneuvering of a core on the mandrel during the winding process.
These and other objects of the present invention are achieved by providing a mandrel system that includes a turret assembly. In general, any turret assembly known in the art can be used in the present invention. Specifically, a turret assembly of the present invention can comprise a plurality of mandrels rotatably affixed to a turret capable of indexing about its longitudinal axis. As such, a mandrel of the present invention can be effectively wound with paper as it rotates.
In one embodiment of the present invention, the turret assembly can index the mandrels into a variety of positions or xe2x80x9cstationsxe2x80x9d at which various portions of the winding process can occur. For instance, a core can be loaded onto a mandrel at one position. A paper web can then be wound on a spinning mandrel at another position. Furthermore, a finished roll of wound paper can be removed at yet another position.
In some embodiments, a mandrel system of the present invention can include a gas circulation system that operates in conjunction with the turret assembly. In general, the gas circulation system can allow the flow of a gas, such as air, through one or more mandrels to aid in positioning, loading, and removing a core located on a mandrel during the winding process. In particular, the gas circulation system can, in some instances, provide a suction force to keep the core held into place on the mandrel. Moreover, the gas circulation system can also, in other instances, provide an outwardly force to the core to aid in loading and removal.
Generally, when utilized with a gas circulation system, mandrels of the present invention typically comprise a hollow channel substantially extending the length of the mandrel and an exterior portion containing a plurality of perforations. As a result, air can easily flow through the mandrel via the hollow channel and plurality of perforations. For instance, when applying a suction force, air can be drawn from outside the mandrel through the perforations such that it exits the mandrel through the hollow channel. Moreover, when applying a positive pressure, air can be forced through the hollow channel such that it exits the mandrel via the plurality of perforations.
In general, the perforations can be positioned on the mandrel in any of a variety of patterns and/or locations. For instance, in one embodiment, the perforations can be distributed along the radial axis of the mandrel such that they extend 360xc2x0 around a cross-section of the mandrel. However, in some instances, the use of less perforations may operate to grip the core more effectively. As such, in some embodiments, the perforations can extend less than 360xc2x0 around a cross-section of the mandrel. For example, in one embodiment, the perforations can be distributed along the radial axis of the mandrel such that they extend about 180xc2x0 around a cross-section of the mandrel. In another embodiment, the perforations can form a spiral pattern about the mandrel.
In some embodiments, it may be desired to selectively provide suction forces and/or air pressure at certain positions of the winding process. For instance, it may be desirable to apply a suction force during paper winding, and yet undesirable to apply a suction force during core loading. As a result, one embodiment of a gas circulation system of the present invention includes a mechanism for controlling the air flow through a particular mandrel. For instance, one or more gas flow control devices can be used to control the flow of air throughout the system.
In fact, in one embodiment of the present invention, two gas flow control devices are used to control the flow of air. In particular, the first gas flow control device contains a vacuum passageway and a pressurized air passageway. A vacuum source can communicate with the vacuum passageway such that a suction force is continuously supplied thereto. Moreover, a pressurized air pump can communicate with the pressurized air passageway such that positive pressure is also continuously supplied thereto. In addition, in one embodiment, the first gas flow control device remains stationary with respect to the indexing turret.
Moreover, in this embodiment, a second gas flow control device can be provided that is rotatably affixed to the turret such that it can index in conjunction therewith. The second gas flow control device can comprise a plurality of air passageways that correspond to a particular mandrel. For example, the second gas flow control device can include six air passageways corresponding to six mandrels. Depending on the position of the turret, each air passageway can be placed in communication with the vacuum passageway or pressurized air passageway of the first gas flow control device as the turret and second gas flow control device rotate.
For example, an air passageway corresponding to a mandrel in the core loading position can be placed in communication with the pressurized air passageway of the first gas flow control device such that a positive pressure can be supplied to the mandrel. Moreover, at the same time, an air passageway corresponding to another mandrel in the paper winding position can be placed in communication with the vacuum passageway of the first gas flow control device such that a suction force can be supplied thereto. In some embodiments, it may also be desired that no positive pressure or vacuum be supplied to a particular mandrel. In that case, the air passageway corresponding to the mandrel is not in communication with either the vacuum or pressurized air passageway of the first gas flow control device.
Other objects, features and aspects of the present invention are discussed in greater detail below.